Grinding machine

ABSTRACT

The grinding machine ( 1 ), in particular for grinding and/or sharpening of knives, comprises a grinding disc ( 2 ), mounted rotatably around a turning axis (D 1 ) and turnable in direction of rotation (D), with a cylindrically-shaped grinding surface ( 2   a ) comprising abrasive means, as well as comprising a guiding part ( 3 ), which is arranged immediately next to the grinding surface ( 2   a ) of the grinding disc ( 2 ), wherein the guiding part ( 3 ) has a guiding surface ( 3   a ) which extends in such a way that the guiding surface ( 3   a ), together with the grinding surface ( 2   a ), forms a gap (S), which progressively tapers in the direction opposite to the direction of rotation (D) and which runs parallel to the direction of the turning axis (D 1 ), and that an overlay part ( 4 ) with an overlay surface ( 4   a ) running towards the gap (S) is arranged immediately next to the grinding surface ( 2   a ) of the grinding disc ( 2 ).

FIELD OF THE INVENTION

The invention concerns a grinding machine.

BACKGROUND OF THE INVENTION

Many grinding machines and grinding apparati are known for grinding orfor re-sharpening of cutting devices, such as knives, or rather, theirblades. Such grinding machines have the disadvantage that it isdifficult to sharpen a blade reproducibly evenly and that, inparticular, this is difficult for people who have limited experiencewith respect to grinding. Thus, it is the problem which this inventionseeks to solve to provide a more advantageous grinding machine.

SUMMARY OF THE INVENTION

In particular, the problem is solved by a grinding machine comprising agrinding wheel with a disc-shaped basic body, wherein the disc-shapedbasic body has a centre of turning, as well as at least one side surfaceextending substantially perpendicularly to the centre of turning, andwherein a grinding disc, having a grinding layer is removably fixable tothe disc-shaped basic body in such a way that the grinding disc isarranged concentrically with respect to the centre of turning andextensionally along the side surface of the disc-shaped basic body, aswell as comprising a support device which forms a guide, wherein theguide is arranged to extend in such a way that at the grinding disc,when this is attached to the basic body, an acute angle γ is formedbetween the grinding layer and the guide, to form a grinding gap.

The grinding machine according to the invention has the advantage,amongst others, that easily-replaceable grinding discs are used asgrinding means. In a particularly preferred embodiment, conventionalgrinding discs may be used which provides the advantage that suchgrinding discs are very cheap. Also grinding discs of varying grain sizecan be used.

In a particularly advantageous embodiment, the grinding disc is coupledelastically with the grinding wheel, in particularly in such a way thatat least a section of the grinding disc is elastically movable in thedirection of extension of the centre of turning, which provides theadvantage that a blade that is to be ground lies particularly softlyagainst the grinding disc, since the latter can adapt to the blade. Thisenables a particularly advantageous blade sharpening.

In a further advantageous embodiment a grinding disc is arranged on eachside of a grinding wheel, such that each side of a blade has its owngrinding disc available to it.

In a particularly advantageous embodiment, the grinding gap is arrangedwith respect to the centre of turning of the grinding disc such that thegrinding disc moves predominantly from bottom to top or alternativelyfrom top to bottom in the area of the grinding gap, which enables aparticularly advantageous sharpening of a blade.

In a further advantageous embodiment, the support device has a rotatablesupport body, which has the advantage that a blade which is moved alongthe support device does not get scratched, and that the blade isparticularly easily movable along the support device.

In the following, the invention is explained by means of an embodimentexample.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 a perspective view of a grinding wheel;

FIG. 2 the grinding wheel shown in FIG. 1 in elevation;

FIG. 3 a longitudinal cross-section through the grinding wheel shown inFIGS. 1 and 2;

FIG. 4 a perspective view of a grinding wheel basic body;

FIG. 5 a perspective view of a grinding disc;

FIG. 6 a perspective view of a grinding machine from the front;

FIG. 7 the grinding machine shown in FIG. 6 in elevation;

FIG. 8 a detail view of the front of the grinding machine shown in FIG.7;

FIG. 9 a further perspective view of the grinding machine from behind;

FIG. 10 a view of the rear side of the grinding machine;

FIG. 11 a view of the grinding machine from above, in partialcross-section;

FIG. 12 a support device in elevation;

FIG. 13 a cross-section through the support device shown in FIG. 12along the line A-A;

FIG. 14 a perspective view of the support device;

FIG. 15 a longitudinal cross-section through a further embodiment of agrinding wheel.

DETAILED DESCRIPTION

FIG. 1 shows a grinding wheel 2 comprising a disc-shaped basic body 2 a,which is fixedly connected with a driveshaft 2 b, and which is rotatablymounted around a turning axis D, or alternatively, a centre of turning Dof the basic body 2 a. One grinding disc 3 is fixed on each of the sidesof the basic body 2 a, on the left side and on the right. The grindingdisc arranged on the left side is shown fully visible and is firmlyconnected with the driveshaft 2 b by means of an underlay disc 2 e and abolt 2 f.

FIG. 2 shows the grinding wheel 2 shown in FIG. 1 in elevation, to whichone grinding disc 3 is fixed on each of the two sides. In the depictedembodiment example, an elastic ring 2 d is arranged between the basicbody 2 a and the grinding disc 3, in order to enable elastic mobility inthe direction extending essentially in the direction of the turning axisD for sections of the grinding disc 3, in particular for sectionsarranged in the vicinity of the elastic ring 2 d.

FIG. 3 shows a cross-sectional through the grinding wheel 2 shown inFIG. 2 along line B-B. The disc-shaped basic body 2 a is firmlyconnected with the driveshaft 2 b. The grinding wheel 2 has a sidesurface 2 g, 2 h on each side, in the outer end section of which, thereis a groove extending circumferentially, in which an elastic means 2 d,such as an elastic O-ring is held.

In the depicted embodiment example, the grinding disc 3 comprises anouter grinding disc part 3 a with a grinding layer 3 a and a preferablymetallic fixation part 3 b, which firmly fixed with the outer grindingdisc part 3 a. The fixation part 3 b has a hole 3 c in the middle. Thegrinding disc 3 can be formed in the most varied of ways such that ithas a grinding layer 3 a. For example, a plastic or a metal disc-shapedbasic body could be used, onto which a grinding layer 3 a has been put.The grinding layer 3 a may, for example, have a plurality of grindinggrains. The width of the usable grinding layer 3 a may, for example,extend over a width 3 d. In a preferred embodiment, the two grindingdiscs 3 are arranged, as shown in FIG. 3, such that they are firmlycentrally held by an underlay disc 2 e and a central bolt 2 f, i.e., arefirmly held at the fixation part 3 b, as opposed to the grinding discs 3which extend from the centre at a distance to the sides 2 g, 2 h andoutwards lie against the elastic O-ring 2 d. This embodiment has theadvantage that, in particular, surfaces of at least section of thegrinding layer 3 a can yield in the direction of extension of theturning axis D, such that the surfaces of the grinding layer 3 a behaverelatively softly and, for instance, can adapt to a blade to besharpened.

FIG. 4 shows a perspective view of the grinding wheel basic body 2 awith side surfaces 2 g, 2 h and a central overlay 2 i. On the rightthere is a grinding disc 3. At least side surface 2 g, and when usingtwo grinding discs, also side surface 2 h, extends substantiallyperpendicularly to the turning axis D. ‘Substantially perpendicularly tothe turning axis’ means, on the one hand, that, in a particularlypreferred embodiment, the side surfaces 2 g, 2 h are perpendicular,i.e., exactly perpendicular, to the turning axis D. On the other hand,this means that in a further advantageous embodiment, the side surfaces2 g, 2 h can also extend at a slight angle to the turning axis, such as,for example conically or crooked.

FIG. 5 shows a perspective view of a grinding disc 3 with grinding layer3 a, fixation part 3 b and hole 3 c. FIG. 5 also shows the preferredgrinding area 3 g, which extends between a horizontal line 3 f that runsthrough the hole 3 and an upper horizontal line 3 e, which preferablyruns at a distance of about 1 cm to 2 cm away from the horizontal line 3f, such that the height 3 h can preferably be up to 2 cm.

FIG. 6 shows a perspective view of an embodiment of a grinding machine1. This comprises a rotatably-mounted grinding disc 3 with a grindinglayer 3 a, which is arranged in a housing 8 with a cover 7 and a frontcover 9. A support device 5, 6 is arranged on the left and on the right,each of which is provided with a magnet 14. Also, there is a sidewaysguide 10. The grinding machine 1 is fixed to a ground plate 4 andcomprises an extraction unit 12 via which air may be extracted frominside the housing 8.

FIG. 7 shows the grinding machine shown in FIG. 6 in elevation and FIG.8 an enlargement of the elevation shown in FIG. 7. The support device 5with guide 5 a, shown on the left, as well as the grinding disc 3 withgrinding layer 3 a, arranged on the left, form a grinding gap S withopening angle γ, wherein the gap S at its bottom, ends in a gap line S1,as shown in FIG. 8. As shown in FIG. 7, the gap line preferably runsperpendicularly towards the rear. In mirrored arrangement to this, thesupport device 6 with guide 6 a, shown on the right, as well as thegrinding disc 3 with grinding layer 3 a, arranged on the right, form agrinding gap S with opening angle γ and gap line S1. Since the grindinglayer 3 a can yield slightly in the direction of extension of theturning axis D, in particular in dependence on the force exerted on thegrinding layer 3 a by the blade to be sharpened, the opening angle γ andthe gap line S1 can alter slightly, which allows particularly ‘soft’grinding. The support devices 5, 6 can be arranged in a fixed manner. Ablade to be sharpened can be laid into the grinding gap S and be movedto and fro in the direction of extension of the gap line S1, in order tosharpen the blade on the rotating grinding layer 3 a. In a particularlypreferred embodiment, the support devices 5, 6 are pivotally arranged insuch a way that the opening angle γ may be adjusted and that the supportdevices 5, 6 can be fixed in the currently desired position. In apreferred embodiment, the adjustable opening angle γ is adjustableacross a range of angles between 15° and 35°. In a preferred embodiment,the gap line S1 is arranged at a vertical distance from the centre ofturning D of the driveshaft 2 b by in the range of between 0 cm and 2cm, preferably between 2 mm and 12 mm. This provides the advantage, asshown in FIG. 5, that the grinding layer 3 a is moving predominantly inthe vertical direction in the area of the gap line S1, since thegrinding disc turns in direction R or counter to R, which, inparticular, provides the advantage that only a small force is exertedacting in the direction of extension of the gap line S1. Due to this,the blade can be particularly easily ground with limited exertion offorce.

FIG. 9 shows a perspective view of the grinding machine 1 and FIG. 10from behind in elevation. FIG. 11 shows the grinding machine 1 fromabove, in partial cross-section. The grinding machine 1 comprising anadjustment device 11 with two rotatable mounted turning axes 11 a, 11 b,which are connected with the left or respectively the right supportdevice 5, 6, in order to alter and adjust their presentation angle andtherewith also the angle γ of the grinding gap S. The grinding machine 1comprises a movably mounted slider 11 h with longitudinal slot 11 l aswell as a locking screw 11 i, which allows the slider 11 h to bereleased and locked. The slider 11 h is also connected with anadjustment grip 11 e, wherein the adjustment grip 11 e engages via ashaft in the longitudinal slot 11 f, 11 g of the levers 11 c, 11 d, andwherein the levers 11 c, 11 d are firmly connected at one end with anaxis of turning 11 a, 11 b, such that pushing the adjustment grip 11 evertically results in a mirrored pivoting of the two axes of turning 11a, 11 b and thereby also of the support devices 5, 6. The adjustmentgrip 11 e can be locked with the help of the locking screw 11 i, therebyalso fixing the position of the support devices 5, 6. In an advantageousembodiment, there is an angle scale 11 k arranged on the rear wall,wherein, based on the positioning of the slider 11 h, the angle size γof the grinding gap S may be read off and adjusted. In a furtheradvantageous embodiment, the grinding machine 1 is firmly and releasablyconnectable with a ground plate 4 via a fixing screw 13.

FIG. 12 shows an embodiment example of a support device 5 in elevation.FIG. 13 shows a cross-section along line A-A shown in FIG. 12 and FIG.14 a perspective view of the support device 5. The support device 5comprises a basic body 5 a with recesses 5 b and releasably-arrangedcylinder-shaped pegs 5 c therein, on which rotatably-mounted supportbodies 5 d are arranged. In the shown embodiment example, the supportbodies 5 d take the form of hollow, cylindrical sleeves. The supportbodies 5 d can take on the most varied of forms, to facilitate a turningsurface or guide 5 e in the direction of extension of the gap line S1.In a particularly advantageous embodiment, a Magnet, preferably apermanent magnet, is arranged in the support device 5, 6, as shown inFIG. 13, such that a metallic, ferromagnetic blade is pulled against thesupport bodies 5 d and lies against them advantageously. This embodimenthas the advantage that the blade lies against the support device 5, 6 ina defined way, such that the blade which is to be sharpened is at adefined angle to the grinding layer 3 a, which results in it beingpossible to grind the blade reproducibly with the same angle, even ifthe blade is only ground, for example, weekly or monthly. Therotatably-mounted support bodies 5 d also have the advantage that theside of the blade that slides past the support bodies 5 d does not getscratched or otherwise damaged.

FIG. 15 shows a longitudinal section that a further embodiment exampleof a grinding wheel 2. Differently to the grinding wheel 2 shown in FIG.3, the grinding wheel 2 shown in FIG. 15 has an elastic means 2 dstretching out over the whole width 3 d of the grinding layer 3 a and onwhich the grinding disc 3 can lie. Instead of being on the Grindingwheel 2, the elastic means 2 d could also be arranged on the rear sideof the grinding disc 3, in particularly in such a way that the elasticmeans 2 d forms part of the grinding disc 3. This embodiment has theadvantage that when a grinding disc 3 is replaced, so is the elasticmeans 2 d, which is thereby as good as new after the replacement. Thisembodiment has the advantage that the elastic properties of whichevergrinding disc 3 is used remain constant or very similar over thelong-term. In a preferred embodiment, the grinding wheel 2 is formedsuch that a conventional and therefore very cheap grinding disc 3 can beused. In addition to this, grinding discs 3 of varying grains could beheld in store, such that a grinding disc 3 of appropriate grain can befixed to the grinding wheel 2 according to particular grindingrequirements. The elastic means 2 d could also be made of such a widthin the radial direction that a majority or all of what is shown as acavity in FIG. 15 is also filled with elastic means 2 d. The elasticmeans 2 d preferably consists of an elastic plastic. The elastic means 2d can be formed in a plurality of possible ways, for example as aspring, in particular as a leaf spring. Thus, for example, a disc-shapedleaf spring could be arranged immediately next to the grinding 3 and itcould be, for example, secured on the shaft 2 b immediately next to thegrinding disc 2, wherein the disc-shaped leaf spring has springyproperties in the direction of extension of the turning axis D, suchthat the grinding disc 3, which is arranged immediately next to the leafspring, similarly has springy properties in the direction of extensionof the turning axis D, due to the leaf spring.

1. A grinding machine (1), comprising a grinding wheel (2) with adisc-shaped basic body (2 a), wherein the disc-shaped basic body (2 a)has a centre of turning (D), as well as at least one side surface (2 g)extending substantially perpendicularly to the centre of turning (D),and wherein a grinding disc (3), having a grinding layer (3 a) isremovably fixable to the disc-shaped basic body (2 a) in such a way thatthe grinding disc (3) is arranged concentrically with respect to thecentre of turning (D) and extensionally along the side surface (2 g) ofthe disc-shaped basic body (2 a), as well as comprising a support device(5, 6) which forms a guide (5 e), wherein the guide (5 e) is arranged toextend in such a way that at the grinding disc (3), when this isattached to the basic body (2 a), an acute angle (γ) is formed betweenthe grinding layer (3 a) and the guide (5 e), to form a grinding gap(S).
 2. Grinding machine according to claim 1, characterised in that thebasic body (2 a) comprises an elastic carrier (2 d) extendingcircumferentially and standing out from the side surface (2 g), whereinthe elastic carrier (2 d) is of a matching form such that an attachedgrinding disc (3) lies against the elastic carrier (2 d).
 3. Grindingmachine according to claim 2, characterised in that the elastic carrier(2 d) is arranged towards the outer periphery of the disc-shaped basicbody (2 a).
 4. Grinding machine according to claim 2, characterised inthat the elastic carrier (2 d) is an O-ring.
 5. Grinding machineaccording to claim 1, characterised in that the basic body (2 a) has anoverly (2 i) in the centre, which stands out from the side surface (2 g)in the direction of extension of the centre of turning (D).
 6. Grindingmachine according to claim 1, characterised in that the grinding wheel(2) is formed on both sides for attaching a grinding disc (3). 7.Grinding machine according to claim 1, characterised in that thegrinding gap (S) ends at its bottom in a gap line (S1), and that thegrinding gap (S) is arranged in a range of between 0 cm to 2 cm,preferably between 2 mm and 12 mm, above a horizontal line (3 f),wherein the horizontal line (3 f) runs through the centre of turning(D).
 8. Grinding machine according to claim 1, characterised in that thesupport device (5, 6) comprises a plurality of rotatably mounted supportbodies (5 d).
 9. Grinding machine according to claim 8, characterised inthat the support bodies (5 d) are arranged next to each other in thedirection of extension of the grinding gap (S).
 10. Grinding machineaccording to claim 8, characterised in that the support means (5, 6)comprises a plurality of basic bodies (5 a), which are arranged next toeach other in the direction of extension of the gap (S), that the basicbodies (5 a) are releasably connected with the support device (5, 6),and that at least one hollow, cylindrically-formed support body (5 d) isrotatably mounted on each basic body (5 a).
 11. Grinding machineaccording to claim 8, characterised in that the support device (5, 6) ispivotally mounted about a turning axis (11 a, 11 b) which issubstantially parallel to the direction of extension of the gap (S). 12.Grinding machine according to claim 11, characterised in that a supportdevice (5, 6) is arranged on each side of the grinding wheel (2), andthat the two support devices (5,6) are pivotally mounted in a mirroredfashion.
 13. Grinding machine according to claim 11, characterised inthat an adjustment device (11) is formed such that it allows a turningand locking of at least one turning axis (11 a, 11 b).
 14. Grindingmachine according to claim 13, characterised in that each of the turningaxes (11 a, 11 b) are connected symmetrically with a shared linearslider (11 h) via a lever (11 c, 11 d), such that a linear moving of theslider (11 h) results in a equal but opposite pivoting of the turningaxes (11 a, 11 b).
 15. Grinding disc for a grinding machine according toclaim 1.